Combustible briquette

ABSTRACT

The present invention provides a composition and method for making combustible briquettes from industrial waste, particularly from industrial fines, which are useful in the manufacture of steel. The fines are mixed with a binder comprising an aqueous solution of sodium silicate, formed into briquettes and dried prior to use.

[0001] The present application claims priority from a ProvisionalApplication filed Jan. 25, 1999, and having U.S. Ser. No. 60/117,121.

FIELD OF THE INVENTION

[0002] The present invention generally relates to combustiblebriquettes. More particularly, the present invention relates tobriquettes comprised of industrial waste, such as fines, which areparticularly useful in the manufacture of iron and steel.

SUMMARY OF THE INVENTION

[0003] The present invention is for combustible briquettes comprised ofindustrial waste products; such combustible briquettes preferablycomprised of industrial fines preferably mixed with a sodium silicatecomponent. One embodiment of the combustible briquette is comprised offerro-silicon fines, where the fines are in a ratio of iron to siliconbeing 1:4, and such fines being mixed with an agglomerating componentwhich is an aqueous mixture of sodium silicate.

[0004] Alternatively, other fines such as silicon alloy, coal, aluminum,ceramics, lead, copper and other industrial waste products, all of whichare typically minute, of a high mesh, such that they are discarded afterthey are produced by traditional industrial processes, are used ascomponents for the combustible briquette.

[0005] One embodiment of a combustible briquette made according to thepresent invention is comprised of the mixture of an aqueous solution ofalkaline water and 10% sodium silicate which is added to ferro-siliconfines, and such mixture is cured within molds to form a hardenedbriquette. Alternatively, a sodium silicate/fine slurry mixture ispoured into a mold and compressed therein to form a hardened briquette.The resultant combustible briquette is water indurant, hard, and durablesufficient to withstand exposure to the elements.

[0006] Due to the sodium silicate binder composition utilized, theresulting combustible briquette exhibits very low pollutant-emittingproperties when it is burned, having low sulfur emissions, particulateemissions, and other noxious gas emissions.

[0007] Therefore, the primary object of the present invention is toprovide a combustible briquette, which can be made from industrial wasteproducts.

[0008] A further object of the present invention is to provide acombustible briquette which has a significantly low pollutant outputwhen combusted.

[0009] Another object of the present invention is to provide aneconomical method of making a combustible briquette from industrialwaste.

[0010] Other features, objects, and advantages of the present inventionwill become apparent after review of the hereinafter set forth DetailedDescription of the Invention.

DETAILED DESCRIPTION OF THE INVENTION

[0011] The present invention is for a combustible briquette, which iscomprised of industrial waste in the form of small particles of dust,powder or fines. A mixture of fines, typically produced and discardedfrom other industrial processes, is used in the present invention. Suchparticles, dust, or fines vary in size depending upon their composition,ranging from about one (1) inch fines to dust particles or powder ofabout 400 mesh size. As one of ordinary skill in the art will readilyappreciate, larger particles greater than approximately ⅜ inch aremeasured in screen size, and can be characterized in inches, whilesmaller particles are measured in mesh size. The present inventivebriquette can be comprised of minute fines even of 400 mesh or larger,where such fines have heretofore typically been considered as wasteproducts requiring disposal. There are numerous fines that can be usedas a component for the combustible briquette, to include iron (Fe),copper (Cu), aluminum (Al), lead (Pb), zinc (Zn), coal, bronze, brass,carbon (C), magnesium (Mg), silicon (Si), manganese (Mn) and can alsoinclude “filter cake,” such as is found in settling ponds of coaltreatment facilities, machine turnings, and material recovered from slagprocessing, dust produced by blast oxygen furnaces, blast furnaces andelectric arc furnaces in their exhaust systems, and “scale” producedfrom mechanical interaction with semi-molten metal in a variety offorms.

[0012] Once the dust or fines are accumulated, they are mixed with anaqueous form of sodium silicate to agglomerate into a combustiblebriquette. Sodium silicate (Na₂Si₄0₉, Na₂Si0₃) is a generic term for afamily of chemicals comprised of sodium oxide Na₂O, silica SiO₂, andtypically water H₂O. Commercial grades of sodium silicate are readilyavailable and fairly inexpensive. For purposes of the present invention,the preferred sodium silicate is either “K” or “STAR” Brand sodiumsilicates from the Philadelphia Quartz Company or the “PQ Corporation.Data sheets and analysis certificates for the K and STAR brands areattached hereto and incorporated herewith. It should be noted that theconcentrations of the aqueous form of the brands are typically altereddepending on final concentrations desired.

[0013] The above materials, or combinations thereof, are preferablymixed with a binder, with 10% sodium silicate by weight being optimum inmost circumstances. Once the sodium silicate in its aqueous form isadded to the industrial waste fines, the resultant mixture can eithercure on its own to dry into a combustible briquette, or pressure isalternately applied to the mixture, typically within a mold, to form abriquette ideal for introduction into a furnace. If compression is usedto form the combustible briquette, it is preferred that low pressure beexerted. For the purpose of this application, low pressure is consideredto be in the range of about 180 psi to about 220 psi, with 200 psi beingoptimum.

[0014] Accordingly, a combustible briquette made according to thepresent invention comprises a mixture of about 90% industrial waste byweight to about 10% binder by weight. The industrial waste, present indifferent sizes ranging from fines of approximately one inch to dustparticles about 400 mesh, comprises iron (Fe), copper (Cu), aluminum(Al), lead (Pb), zinc (Zn), coal, bronze, brass, carbon (C), magnesium(Mg), silicon (Si), manganese (Mn), “filter cake”, machine turnings,slag processing waste, furnace dust, scale and mixtures thereof.

[0015] Water is also a component of the industrial waste, with theamount of water varying depending upon the type of industrial wasteused. For example, waste material containing sludge contains thegreatest amount of water; fines from electric arc furnaces, blastfurnaces or blast oxygen furnaces contains the least water; and otherindustrial waste materials contain water in an amount intermediatebetween sludge waste and fines from furnaces. The industrial waste isadded in a variety of sizes ranging from particles of about one (1) inchto power or dust about 400 mesh or larger. The pH of the resultingmixture ranges from slightly acidic to slightly basic; that is, from apH of about 6.0 to a pH of about 8.0; preferably from about pH 6.5 toabout pH 7.5, and most preferably a pH of about 7.0.

[0016] The binder, present in the industrial waste/binder mixture atabout 10% by weight, is sodium silicate. In one embodiment, the finesare mixed with a binder comprising 10% aqueous “K” brand sodium silicatesolution (10% sodium silicate, 90% H₂O). The industrial waste/bindermixture is mixed throughly, such that the particles are evenly dispersedbefore forming the mixture into briquettes.

[0017] In one embodiment, the industrial waste/binder mixture is formedinto briquettes allowing the mixture to cure within molds. In analternate embodiment, the briquettes are subject to low pressure in therange of about 180 psi to about 220 psi, with 200 psi being optimum.

[0018] Additionally, the dry combustible briquettes are alternatelysubjected to additional drying heat to further harden prior combustionin a furnace, if so desired. When intended to be used in a blastfurnace, moisture can cause the briquettes to explode. Thus, in suchapplication, drying to remove all moisture from the briquette would benecessary. It is accordingly recommended that the briquettes be dried ina range of 350-450° F. for at least 6 hours, although, other dryingtemperatures and times are alternately used dependant on the resultdesired.

[0019] In an alternate embodiment, the briquette may be dried byapplying heat less than 750° F. (approximately the ignition temperatureof carbon), preferably between about 350° F. to about 600° F., and mostpreferably about 500° F. As is apparent to one of ordinary skill in theart, the drying time required to completely dry the briquettes variesaccording to a number of factors, such as amount of air circulation,type of heat used for drying, and amount of moisture in the industrialwaste/binder mixture.

[0020] Briquettes formed according to the present invention will vary insize depending upon a number of factors, such as size of the mold usedfor briquette formation. The preferred size is greater than 2 in ×2 in,or 2 inches long and 2 inches in diameter, although greater sizes havingother dimensions are alternatively used. For example, in one embodimentthe briquette is formed into a 2 inch by 3 inch cylinder, measuring 2inches in diameter by 3 inches in height.

[0021] A combustible briquette produced in such manner results in a lowpollutant emitting combustion burn, which is smokeless, emits very fewparticulates, as well as noxious gases such as nitrous oxide, sulfur,and carbon monoxide.

[0022] Additionally, the present inventive combustible briquettes areideal in use in the formation of steel. For example, using silicon inthe sodium silicate binder of the present invention produces acombustible briquette which is quite desirous for use in steelproduction, either being added in the initial furnace with the iron, orlater in the blast oxygen furnace for the actual production of steel.The inventive briquettes are also likewise useful in the production ofsteel or steel-alloys in electric arc furnaces.

[0023] While there has been shown the preferred and altering embodimentsof the present invention, it is to be understood that certain changesmay be made in the forms and arrangements of the combustible briquetteand method of manufacture, without departing from the spirit and scopeof the invention as set forth in this disclosure.

We claim:
 1. A method for forming a combustible briquette comprising thesteps of: obtaining industrial waste fines; adding the fines to a bindercomprising an aqueous solution of sodium silicate; mixing the fines andthe sodium silicate mixture throughly; forming the mixture in a mold;and subjecting the mixture to a pressure to form a briquette.
 2. Themethod of claim 1, wherein the pressure is from about 180 psi to about220 psi.
 3. The method of claim 1, wherein the pressure is about 200psi.
 4. The method of claim 1 wherein the mixture comprises 10% sodiumsilicate by weight.
 5. The method of claim 1 wherein said fines arechosen from a group consisting of iron, silicon, coal, aluminum,ceramics, lead, zinc, copper, magnesium, manganese, silicon, bronze,brass, and mixtures thereof.
 6. The method of claim 1 wherein said finescomprise ferro-silicon.
 7. The method of claim 6 wherein theferro-silicon fines are in a ratio of iron to silicon of 1:4.
 8. Themethod of claim 1 wherein said fines comprise iron.
 9. The method ofclaim 1 wherein the aqueous solution is at a pH of about 6.0 to about8.0.
 10. The method of claim 1 wherein the aqueous solution is at a pHof about 7.0.
 11. The method of claim 1 having said fines ranging insize from about 1 inch to about 400 mesh.
 12. The method of claim 1wherein said briquette is dried using heat in the range of about 350° F.to about 600° F.